问题
单项选择题
The long-run production decision differs from the short-run production decision in that:（）
A. variable costs can be changed in the short run but not the long run.
B. variable costs can be changed in the long run but not the short run.
C. fixed costs can be changed" in the long run but not the short run.
答案
参考答案：C
解析：
The long-run production decision differs from the short-run production decision in that fixed costs can be changed in the long run but not the short-run. Thus, short-run cost curves apply for a given size of a plant, and long-run cost curves can show costs for different size plants.